Now, days after a jury found Zimmerman not guilty, they are back to address the NAACP national convention in Orlando Wednesday.

News of their appearances surfaced just before a significant NAACP update: 1 million signatures have been gathered as of Tuesday for an online petition urging the U.S. Department of Justice to file federal charges, including civil-rights charges, against Zimmerman.

"This major milestone was reached in just two and a half days," a statement today said.

That number is likely to grow before the high-profile speakers arrive Wednesday.

Jackson and Sharpton will be joined by Martin Luther King III, and are scheduled to speak at the convention's final plenary session at 9 a.m. Wednesday, along with Rep. Debbie Wasserman Shultz and others, according to Derek Turner, NAACP director of communications.

The Trayvon Martin shooting case, and verdict, are likely to be among the topics discussed.

In the weeks following Trayvon's shooting on Feb. 26, 2012, as Sanford police persisted in their decision not to arrest Zimmerman, thousands of protesters took to the streets.

Jackson and Sharpton led those marches and rallies in Sanford in March 2012, calling for Zimmerman's arrest. He was arrested and charged in April 2012.

Neither Jackson nor Sharpton appeared in Central Florida during the trial, as some case observers thought they might, but both released statements after the verdict was reached Saturday night.

"The acquittal of George Zimmerman is a slap in the face to the American people but it is only the first round in the pursuit of justice," Sharpton wrote in a statement. "We intend to ask the Department of Justice to move forward as they did in the Rodney King case and we will closely monitor the civil case against Mr. Zimmerman."

Sharpton said then that he would "head to Florida in the next few days."

Jackson took to Twitter late Saturday, urging calm.

"Avoid violence, it will lead to more tragedies. Find a way for self construction not deconstruction in this time of despair. #ZimmermanTrial," Jackson tweeted.